Iskanje po katalogu digitalne knjižnice

Opis: In this study, using an in-situ, air-flow test in Essen, the impacts of different factors on multiphase flow and land uplift during and after compressed-air injection were investigated using numerical simulations. A loosely coupled, two-phase flow and geo-mechanical modeling approach, linking two numerical codes (TOUGH2/EOS3 and FLAC3D) was employed to simulate the in-situ, air-flow test for comparing the simulated and measured results. As the compressed air is injected, it flows upwards and laterally, and the vertical effective stress near and above the injection zones decreases owing to the pore pressure increasing here, causing an expansion of the soil skeleton in the corresponding zones. The land uplift, induced mainly by support actions from lower deformed soils, is relevant to the distribution of the porosity increments in the soil interior, and it increases rapidly during air injection. After the compressed-air injection stops, the land uplift decreases gradually to zero due to the overpressure dissipation. With a combination of intensive rainfall, the land uplift is slightly greater near the borehole, but it is significantly greater at a distance from the borehole than the land uplift with no or low rainfall, but the air-injection rate remains almost unchanged due to the unchangeable pore pressure near the injection region. As the intrinsic permeability increases or the air entry pressure decreases in the injected strata, both the land uplift and the air injection rate increase, but the time required for the land uplift to become zero is slightly advanced with either a small permeability or a high air entry pressure.
Ključne besede: loosely coupled two-phase flow and geo-mechanical model, in-situ, air-flow test, compressed-air injection, multiphase flow, land uplift, air loss
Objavljeno v DKUM: 18.06.2018; Ogledov: 1192; Prenosov: 181
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Opis: On 5 October 2015, the Trans-Pacific Partnership Agreement (TPP) led by the U.S. was signed. Already, 12 countries1 have joined the agreement, but China has not. Thus, lots of research has focused on the negative effect of the TPP on China’s foreign trade. On the other hand, China is moving forward in its own efforts to establish bilateral free trade agreements (FTAs) and free trade zones. In June 2015, China-South Korea and China-Australia signed bilateral FTAs which went into effect in December 2015. Several questions were raised: Since South Korea and Australia are the major trade partners in the Pacific area and the bilateral FTAs will be effective before the TPP, will these FTAs’ positive effects on China’s foreign trade offset some of the negative effects of the TPP? If China and the U.S. adopted a competitive trade policy, which countries would benefit? If China and the U.S. adopted a cooperative trade policy, how would the trade value and economic welfare change? This paper simulates and analyses the mutual effects of China-South Korea and China-Australia FTAs and the enlarging TPP using the computable general equilibrium model. The major conclusions drawn suggest that China-South Korea and China-Australia FTAs will significantly offset the TPP’s negative effect on China’s foreign trade. If China is not included, the U.S. economic benefit from the TPP will be limited. The economic welfare for a country like Australia, which joined both the bilateral FTA and the TPP, will be increased the most. In the long run, China joining the TPP would be the most beneficial decision for its national interest. However, if the TPP cannot be approved by the US congress, the U.S.’s economic indicators and export would be decreasing sharply. China’s economy and export will benefit from FTAs.
Ključne besede: China-South Korea FTA, China-Australia FTA, TPP, interaction effects
Objavljeno v DKUM: 03.05.2018; Ogledov: 1175; Prenosov: 306
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Opis: Despite the increasing interest in model-driven engineering, there are many open issues that need to be addressed to advance the technology and promote its adoption. This position paper outlines several current limitations of model transformation, with a specific emphasis on model optimization. A primary shortcoming that can be found in many model transformation approaches and tools is the lack of formal semantics to define the meaning of a modeling abstraction. This inadequacy is the source of many problems surrounding the practice of model engineering.
Ključne besede: domain-specific languages, program transformation, model transformation, model-driven engineering, modeling language
Objavljeno v DKUM: 31.05.2012; Ogledov: 2177; Prenosov: 47
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